2007 rear differential help

[Sidd]

Hello everyone,I recently purchased a 2007 x3 at a very low price wish some issues so the most important is a sound coming from the rear differential while running. It sounds just like a bad bearing however the weird part is that whenever I turn the car off I can hear fro this differential a sound just like an electric small motor still running (even car is off) this sound lasts for about 4-5 minutes then it stops. Can somebody help?. I was wondering if the problem is the full differential would there be a way to disable the 4x4 system? Doesn't matter if the car is just fwd as long as it drives an I don't have to break the bank with a repair. Help will be appreciated.

[Greydog]

Morning Siddhartha

Welcome to the Forum

Your X3 is fitted with a front and rear diffs connected through a transfer box at the back of the gearbox. The diffs front and rear have no pump attached so the fact that you say you can hear something running I would suspect the following as suspects. (1) air re-circulation fans and auxiliary water pump which can run for 5 mins after shut down  to protect the turbo. (2) If you have rear air suspension the pump can run to maintain pressure it will normally only run up to the point the car goes to sleep. If it is running for 5 mins I would suspect a leak, the suspension pump is in the boot.

Dave